Expandable interspinous process fixation device

ABSTRACT

An expandable interspinous process fixation system capable of restoring spinal stability and facilitating fusion. In one embodiment, the expandable interspinous process fixation system includes a central ramp, a first endplate, and a second endplate, the central ramp capable of being moved in a first direction to move the first and second endplates outwardly and into an expanded configuration. Each endplate supporting fixed and/or adjustable spinous process engaging plates.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No.15/635,267, filed Jun. 28, 2017, which is a continuation-in-part of U.S.application Ser. No. 15/189,188, filed Jun. 22, 2016, now U.S. Pat. No.10,085,849, which is a continuation-in-part of U.S. application Ser. No.15/014,189, filed Feb. 3, 2016, now U.S. Pat. No. 9,907,673, which is acontinuation-in-part of U.S. application Ser. No. 14/109,429, filed Dec.17, 2013, now U.S. Pat. No. 9,370,434, which is a divisional of U.S.patent application Ser. No. 12/875,818, filed Sep. 3, 2010, now U.S.Pat. No. 8,632,595, the entire disclosures of which are incorporatedherein by reference in their entireties for all purposes.

FIELD OF THE INVENTION

The present disclosure is generally directed to surgical devices,systems, and methods. More particularly, the present disclosure isdirected to expandable interspinous process fixation devices, systems,and methods.

BACKGROUND

A spine comprises vertebrae which are a series of small bones, and alsoincludes spinous processes. A spinous process is one of two bonyprotrusions arising from the posterior side of each vertebra in thehuman spine. Extending backwards and downwards from the main body of thevertebra, each spinous process is an extension of the lamina. Thelaminae are two bony plates that converge at the back of each vertebrato form the vertebral arch. The spinous processes curve outward fromthis junction. A variety of scenarios may exist where damage to thespine may occur including, but not limited to, injury or illness.Severe, even debilitating, pain can result from such damage. In someinstances, artificial assistance may be necessary to address suchdamage.

Surgical procedures exist that attempt to address such damage includingusing various vertebral fixation devices. Conventional devices exist toimplant vertebrae fixation devices, but such devices often suffer fromthe problem of being purely manual and are usually complex. Such manualdevices require the use of human muscle, which can fatigue, to performthe procedure. Moreover, the incision opening for insertion of thesefixation devices may require substantial openings to achieve access tothe spinous process.

There are drawbacks associated with the known conventional fixationdevices and methodologies. For example, present methods for installing aconventional fixation device often require that the adjacent vertebralbodies be distracted to restore a diseased disc space to its normal orhealthy height prior to implantation of the fixation device. In order tomaintain this height once the fixation device is inserted, the fixationdevice is usually dimensioned larger in height than the initialdistraction height. This difference in height can make it difficult fora surgeon to install the fixation device in the distractedintervertebral space.

As such, there exists a need for a fixation device capable of beinginstalled inside an intervertebral disc space at a minimum to nodistraction height and for a fixation device that can maintain a normaldistance between adjacent vertebral bodies when implanted.

SUMMARY

To meet this and other needs, devices, systems, and methods of fixationare provided. The fixation devices and systems may include expandableinterspinous process fixation devices and system and associated methodof implantation.

In at least one embodiment, the present disclosure provides anexpandable interspinous process fixation system which is a posterior,non-pedicle supplemental fixation device. In some embodiments, theinterspinous process fixations system may be intended for use in thenon-cervical spine. The interspinous process fixations system may attachfirmly to adjacent spinous processes and immobilize a lumbar motionsegment posteriorly. The device may be configured to withstandcompressive, torsional, and shear loads seen in the lumbar spine. Thedevice is intended to achieve supplemental fusion, treating variousconditions, for example, degenerative disc disease; spondylolisthesis;trauma (i.e., fracture or dislocation); tumor; and/or other conditions.

In at least one embodiment, a device according to the present disclosureallows for insertion of a spinous process fixation implant at a reducedheight and then an increase of the height after insertion to achieve anaccurate anatomical fit. Adjustability of the implant greatly reducesthe complexity of inserting an interspinous device since one devicecovers a wide range of implant sizes, negating the need for severalvariations of implant lengths and widths. The implant may bepreassembled, greatly reducing the number of steps required to insertthe device, which simplifies the overall procedure and reduces operatingroom time.

In at least one embodiment, the present disclosure provides a fixationdevice including first and second endplates for an intervertebralimplant. The first endplate has a first lateral adjustment arm extendingfrom a first edge thereof and the second endplate has a second lateraladjustment arm extending from a first edge thereof. A first fixed plateextends along a second edge of the first endplate opposite the firstedge thereof. The first fixed plate extends substantially perpendicularto the first endplate and has an inner surface defining a first spinousprocess engaging surface. A second fixed plate extends along a secondedge of the second endplate opposite the first edge thereof. The secondfixed plate extends substantially perpendicular to the second endplateand has an inner surface defining a second spinous process engagingsurface. A first sliding plate is adjustably mounted on the firstlateral adjustment arm such that the first sliding plate extendssubstantially perpendicular to the first endplate and has an innersurface defining a third spinous process engaging surface. A secondsliding plate is adjustably mounted on the second lateral adjustment armsuch that the second sliding plate extends substantially perpendicularto the second endplate and has an inner surface defining a fourthspinous process engaging surface. An expansion assembly is positionedbetween the first and second endplates and is configured to selectivelycause the first and second endplates to move apart.

In at least one embodiment, the present disclosure provides a methodincluding: inserting an expandable fixation device into anintervertebral disc space, wherein the expandable fixation deviceincludes: a first endplate for an intervertebral implant, the firstendplate having a first lateral adjustment arm extending from a firstedge thereof; a second endplate for an intervertebral implant, thesecond endplate having a second lateral adjustment arm extending from afirst edge thereof a first fixed plate extending along a second edge ofthe first endplate opposite the first edge thereof, the first fixedplate extending substantially perpendicular to the first endplate andhaving an inner surface defining a first spinous process engagingsurface; a second fixed plate extending along a second edge of thesecond endplate opposite the first edge thereof, the second fixed plateextending substantially perpendicular to the second endplate and havingan inner surface defining a second spinous process engaging surface; afirst sliding plate adjustably mounted on the first lateral adjustmentarm such that the first sliding plate extends substantiallyperpendicular to the first endplate and has an inner surface defining athird spinous process engaging surface; a second sliding plateadjustably mounted on the second lateral adjustment arm such that thesecond sliding plate extends substantially perpendicular to the secondendplate and has an inner surface defining a fourth spinous processengaging surface; an expansion assembly positioned between the first andsecond endplates; the expansion assembly configured to selectively causethe first and second endplates to move apart; actuating the expansionassembly to cause movement of the first and the second endplates awayfrom one another; adjusting the lateral position of the first slidingplate such that spinous processes are compressed between the first andthird spinous process engaging surfaces and thereafter fixing theposition of the first sliding plate; and adjusting the lateral positionof the second sliding plate such that spinous processes are compressedbetween the second and fourth spinous process engaging surfaces andthereafter fixing the position of the second sliding plate.

Additional features, advantages, and aspects of the present disclosuremay be set forth or apparent from consideration of the followingdetailed description, drawings, and claims. Moreover, it is to beunderstood that both the foregoing summary of the present disclosure andthe following detailed description are exemplary and intended to providefurther explanation without limiting the scope of the present disclosureas claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the present disclosure, are incorporated in andconstitute a part of this specification, illustrate aspects of thepresent disclosure and together with the detailed description serve toexplain the principles of the present disclosure. No attempt is made toshow structural details of the present disclosure in more detail thanmay be necessary for a fundamental understanding of the presentdisclosure and the various ways in which it may be practiced. In thedrawings:

FIG. 1 is a perspective view of the expandable fixation device inaccordance with one embodiment of the present disclosure shown in anunexpanded position;

FIG. 2 is a front elevation view of the expandable fixation device ofFIG. 1 in the unexpanded position;

FIG. 3 is an exploded perspective view of the expandable fixation deviceof FIG. 1;

FIG. 4 is a left side view of the expandable fixation device of FIG. 1in the unexpanded position;

FIG. 5 is a right side view of the expandable fixation device of FIG. 1in the unexpanded position;

FIG. 6 is a perspective view of the expandable fixation device of FIG. 1shown in an expanded position;

FIG. 7 is a front elevation view of the expandable fixation device ofFIG. 1 in the expanded position;

FIG. 8 is a left side view of the expandable fixation device of FIG. 1in the expanded position;

FIG. 9 is a right side view of the expandable fixation device of FIG. 1in the expanded position;

FIG. 10 is a perspective view of the expandable fixation device inaccordance with another embodiment of the present disclosure shown in anexpanded position;

FIG. 11 is an exploded perspective view of the expandable fixationdevice of FIG. 10;

FIG. 12 is a left side view of the expandable fixation device of FIG. 10in an unexpanded position;

FIG. 13 is a right side view of the expandable fixation device of FIG.10 in the unexpanded position;

FIG. 14 is a right side view of the expandable fixation device of FIG.10 in an intermediate position;

FIG. 15 is a left side view of the expandable fixation device of FIG. 10in the expanded position; and

FIG. 16 is a right side view of the expandable fixation device of FIG.10 in the expanded position.

DETAILED DESCRIPTION

The aspects of the present disclosure and the various features andadvantageous details thereof are explained more fully with reference tothe non-limiting aspects and examples that are described and/orillustrated in the accompanying drawings and detailed in the followingdescription. It should be noted that the features illustrated in thedrawings are not necessarily drawn to scale, and features of one aspectmay be employed with other aspects as the skilled artisan wouldrecognize, even if not explicitly stated herein. Descriptions ofwell-known components and processing techniques may be omitted so as tonot unnecessarily obscure the aspects of the present disclosure. Theexamples used herein are intended merely to facilitate an understandingof ways in which the present disclosure may be practiced and to furtherenable those of skill in the art to practice the aspects of the presentdisclosure. Accordingly, the examples and aspects herein should not beconstrued as limiting the scope of the present disclosure, which isdefined solely by the appended claims and applicable law. Moreover, itis noted that like reference numerals represent similar parts throughoutthe several views of the drawings.

Surgical intervention for back pain may occur for people with chronicback pain, perhaps for which other treatments have failed. Surgery maybe required, for example, for people who have chronic lower back painand sciatica (often diagnosed with a herniated disc), spinal stenosis,spondylolisthesis (vertebra of the lumbar spine slips out of place),vertebral fractures with nerve involvement, or other indications asassessed by a medical professional. Also, surgery may be necessary forpeople with discogenic lower back pain (e.g., degenerative disc disease)that may occur as part of the aging process. In these situations, amongothers, implants may be included in a course of treatment. Generally,the goal may be to achieve supplemental fusion or complete fusion of thespine.

With reference to FIGS. 1-9, an embodiment of the fixation device 10 isshown. In the exemplary embodiment, the fixation device 10 includes afirst endplate 20, a second endplate 40, first and second fixed plates60, 70, a pair of sliding plates 80, 90, a central ramp 110, and adriving ramp 130.

Each of the endplates 20, 40 includes a body 22, 42 extending betweenopposed ends 21, 23; 41, 43. In the illustrated embodiment, eachendplate body 22, 42 defines an outer surface 24, 44 connecting thefirst end 21, 41 and the second end 23, 43, and an inner surface 26, 46connecting the first end 21, 41 and the second end 23, 43. In anembodiment, each endplate 20, 40 defines a through opening 25, 45. Thethrough openings 25, 45, in an exemplary embodiment, are sized toreceive bone graft or similar bone growth inducing material and furtherallow the bone graft or similar bone growth inducing material to bepacked in a central area of the device 10.

The outer surface 24, 44 of each endplate 20, 40 may be flat andgenerally planar to allow the outer surface 24, 44 of the endplate 20,40 to engage with an adjacent vertebral body. Alternatively, one or bothof the outer surfaces 24, 44 can be curved convexly or concavely toallow for a greater or lesser degree of engagement with the adjacentvertebral body. It is also contemplated that the outer surfaces 24, 44can be generally planar but include a generally straight ramped surfaceor a curved ramped surface, angled, or otherwise configured. Thepresence of one or more ramped surfaces may allow for engagement withthe adjacent vertebral body in a lordotic fashion. While notillustrated, in an exemplary embodiment, one or both outer surfaces 24,44 may include texturing or other surface features to aid in grippingthe adjacent vertebral bodies. Although not limited to the following,the texturing or other surface features can include teeth, ridges,friction increasing elements, keels, gripping or purchasing projections,or the like.

Referring to FIGS. 3, 5 and 9, the inner surface 26 of the firstendplate 20 defines a first pair of spaced apart extensions 30 at thefirst end 21 of the body 22 and a second pair of spaced apart extensions34 at the second end 23 of the body. The extensions 30 at the first end21 are positioned oppositely of the extensions 34 at the second end 23,e.g., on the first end 21, the extension 30 on the right side is at theedge while the extension on the left side is inward of the edge and onthe second end 23, the extension 34 on the right side is inward of theedge while the extension on the left side is at the edge. Similarly, theinner surface 46 of the second endplate 40 defines a first pair ofspaced apart extensions 50 at the first end 41 of the body 42 and asecond pair of spaced apart extensions 54 at the second end 43 of thebody. With the second endplate 40, the extensions 50, 54 are opposite ofthose on the first plate 20 i.e. on the first end 41, the extension 50on the right side is inward from the edge while the extension on theleft side is at the edge and on the second end 43, the extension 54 onthe right side is at the edge while the extension on the left side isinward of the edge. With this configuration, the extensions 30 of thefirst endplate 20 overlap the extensions 50 of the second endplate 40and the extensions 54 of the second endplate 40 overlap the extensions34 of the first endplate 20.

Each of the extensions 30, 34, 50, 54 defines a respective rampedsurface 31, 35, 51, 55. The ramped surfaces 31, 35, 51, 55 areconfigured to be engaged by ramped surfaces on the central ramp 110 andthe driving ramp 130, as will be described hereinafter. Each of theextensions 30, 34, 50, 54 also defines a respective groove 33, 37, 53,57. The grooves 33, 37, 53, 57 are configured to be engaged byprojections on the central ramp 110 and the driving ramp 130 to maintainthe device 10 in an assembled condition and to guide movement of theendplates 20, 40, as will be described hereinafter.

Each endplate 20, 40 includes a fixed plate 60, 70 attached along oneside edge of the body 22, 42. Each fixed plate 60, 70 of the illustratedembodiment includes a body 62, 72 extending from a fixed end 61, 71 to afree end 63, 73. The fixed plate bodies 62, 72 may have any desiredshape to complement the intended engagement with respective spinousprocesses, and may be mirror images of one another or may be distinctfrom one another. The inner surface 64, 74 of each fixed plate 60, 70includes a plurality of spikes 66, 76 or the like to grip the spinousprocesses when engaged therewith. The outer surface of each fixed platemay include a blind bore 67, 77, through bore or the like. The bores 67,77, in an exemplary embodiment, are sized to receive bone graft orsimilar bone growth inducing material.

A lateral adjustment bar 28, 48 extends outwardly from the opposite sideedge of the body 22, 42 of each end plate 20, 40 to a free end 29, 49.The adjustment bars 28, 48 support respective sliding plates 80, 90.Each sliding plate 80, 90 of the illustrated embodiment includes a body82, 92 extending from a connection end 81, 91 to a free end 83, 93. Thesliding plate bodies 82, 92 may have any desired shape to complement theintended engagement with respective spinous processes, and may be mirrorimages of one another or may be distinct from one another. The innersurface 84, 94 of each fixed plate 80, 90 includes a plurality of spikes86, 96 or the like to grip the spinous processes when engaged therewith.The outer surface of each fixed plate may include a blind bore 87, 97,through bore or the like. The bores 87, 97, in an exemplary embodiment,are sized to receive bone graft or similar bone growth inducingmaterial.

The connection end 81, 91 of each sliding plate 80, 90 includes aconnection assembly 88, 98 which allows the sliding plate 80, 90 to bemounted on a respective lateral adjustment bar 28, 48 such that thesliding plate 80, 90 is laterally adjustable but rotationally fixed. Inthe illustrated embodiment, each connection assembly 88, 98 defines areceiving bore 85, 95 extending laterally through the body 82, 92 andconfigured to receive the respective lateral adjustment bar 28, 48. Thereceiving bores 85, 95 and the lateral adjustment bars 28, 48 havecomplementary shapes which allow lateral adjustment but prevent relativerotation. In the illustrated embodiment, the receiving bores 85, 95 andlateral adjustment bars 28, 48 have complementary rounded rectangleshapes, but other non-circular shapes are possible.

To set the position of the sliding plate 80, 90 along the respectivelateral adjustment bar 28, 48, a set screw 100 extends into a throughbore 89, 99 defined in the respective connection assembly 88, 98 andintersects with the receiving bore 85, 95. Each set screw 100 includes athreaded portion 102 and a driving head 104 with an engagement end 103extending toward the receiving bore 85, 95. The threaded portion 102 isconfigured to engage threads within the through bore 89, 99. A retainingring 105 or the like may be positioned about each set screw 100 andengage a groove within the through bore 89, 99 to retain the set screw100 with the through bore 89, 99 after assembly. Once the sliding plate80, 90 is positioned at a desired lateral position along the respectivelateral adjustment bar 28, 48, the set screw 100 is threadably advancedsuch that the engagement end 103 engages the lateral adjustment bar 28,48 and fixes the sliding plate 80, 90 relative to the respectiveendplate 20, 40.

The central ramp 110 includes a body 112 extending from a first end 111to a second end 113. A through bore 114 extends through the body 112from the first end 111 to the second end 113 and is configured toreceive a drive screw 120 therethrough. The drive screw 120 has athreaded portion 122 and drive head 124. A flat washer 126 and a dragreducing washer 128 may be positioned within the through bore 114between the drive head 124 and an internal shoulder defined within thethrough bore 114 (not show) to facilitate driving of the central rampwhile minimizing drag. Notches 119 or the like may be defined along thecentral ramp body 112 configured for engagement with adelivery/positioning tool (not shown) or the like.

The second end 113 of the central ramp 110 defines a first pair of ramps116 and a second pair of ramps 117. The first ramps 116 are aligned withand configured to slidably engage the ramps 31 on the first endplate 20.The second ramps 117 are aligned with and configured to engage the ramps51 on the second end plate 40. Projections 118 adjacent the ramps 116extend into the grooves 33 on the first endplate 20 while projectionadjacent to the ramps 117 (not shown) extend into the grooves 53 on thesecond endplate 40. Engagement between the projections 118 and grooves33, 53 maintains the central ramp 110 assembled to the endplates 20, 40and guides movement of the endplates 20, 40 as the central ramp 110 isadvanced.

The driving ramp 130 includes a ramp body 132 and a screw receivingportion 134. A threaded blind bore 139 extends into the screw receivingportion 134 and is configured to receive the threaded portion 122 of thedrive screw 120. As such, rotation of the drive screw 120 in theadvancement direction causes the central ramp 110 and the driving ramp130 to move toward one another.

The ramp body 132 of the driving ramp 130 defines a pair of first ramps136 and a pair of second ramps 137 (see FIG. 3). The first ramps 136 arealigned with and configured to slidably engage the ramps 55 on thesecond endplate 40. The second ramps 137 are aligned with and configuredto engage the ramps 35 on the first end plate 20. Projections 138adjacent the ramps 136 extend into the grooves 57 on the second endplate40 while projections 138 adjacent to the ramps 137 extend into thegrooves 37 on the first endplate 20. Engagement between the projections138 and grooves 37, 57 maintains the driving ramp 130 assembled to theendplates 20, 40 and guides movement of the endplates 20, 40 as thedriving ramp 130 is advanced.

Having generally described the components of the fixation device 10,operation thereof will generally be described. The fixation device 10may be inserted at its fully collapsed height as illustrated in FIGS. 1,2, 4 and 5 to allow for easy insertion into a collapsed interspinousspace. During insertion, the spikes 66, 76 of the fixed plates 60, 70may be compressed into the respective spinous processes. Afterinsertion, the fixation device 10 may be expanded by rotating the drivescrew 120 in an advancement direction. As the drive screw 120 isrotated, the central ramp 110 and driving ramp 130 are drawn toward oneanother, with the ramps 31 riding up the ramps 116, the ramps 51 ridingup the ramps 117, the ramps 35 riding up the ramps 137, the ramps 55riding up the ramps 136. Such movement causes the endplates 20, 40 tomove away from one another, thereby increasing the height of thefixation device 10 to get the desired fit, or used to distract theinterspinous space to relieve pressure on neurological elements. As theendplates 20, 40 move away from one another, the fixed plates 60, 70 andsliding plates 80, 90 move in conformity therewith. After expansion ofthe endplates 20, 40, the sliding plates 80, 90 are moved along thelateral adjustment bars 28, 48 and compressed onto the spinousprocesses. Once positioned, the sliding plates 80, 90 are locked intoposition using the set screws 100.

Referring to FIGS. 10-16, another embodiment of the fixation device 10′is shown. The fixation device 10′ of the present exemplary embodiment issimilar to the fixation device 10 of the previous embodiment andincludes a first endplate 20′, a second endplate 40′, first and secondfixed plates 60, 70, a pair of sliding plates 80, 90, a central ramp110′, and a driving ramp 130′. Only the differences between theembodiments will be described. Otherwise, the fixation devices 10, 10′operate is substantially the same manner.

In the present embodiment, the endplates 20′ and 40′ and the centralramp 110′ are configured to cause pivoting between the endplates 20′,40′ prior to expansion thereof. As in the previous embodiment, eachendplate 20′, 40′ includes a body 22′, 42′ extending from a first end21′, 41′ to a second end 23′, 43′. Referring to FIG. 14, in the presentembodiment, the first ends 21′, 31′ do not include extensions, butinstead have a tapered end surface which defines the ramps 31′ 51′. Thesecond ends 23′, 43′ are similar to the previous embodiment and includeextensions 34′, 54′ defining the ramps 35, 55. The extensions 34′ 54′also define inward ramps 36, 56. Inward of the extensions 34, 54, eachendplate body 22′, 44′ defines a retaining notch 29, 49. The retainingnotches 29, 49 are configured to be engaged by an inward end 113′ of thecentral ramp 110′ and prevent inward advancement of the central ramp110′ until the endplates 20′ 40′ have pivoted relative to one another.

The central ramp 110′ includes a body 112′ extending from a first end111′ to a second end 113′ with the body 112′ having a longer lengthcompared to the central ramp body 112 of the previous embodiment. Athrough bore 114 extends through the body 112′ from the first end 111′and is configured to receive the drive screw 120 therethrough. The firstend 111′ of the central body 110′ defines ramps 116′ and 117′. The ramps116′ and 117′ are configured to engage the ramps 31′ and 51′,respectively.

The second end 113′ of the central ramp 110 defines a pair of extensions123 on a first surface thereof and a pair of extensions 125 on theopposite surface. The extensions 123 are aligned with and configured tobe received in the notches 29 defined by the first endplate 20′ and theextensions 125 are aligned with and configured to be received in thenotches 49 defined by the second endplate 40′ (see FIG. 13). Theextensions 123 also define forward ramps 127 while the extensions 125define forward ramps 129.

The driving ramp 130′ includes a ramp body 132′ and a screw receivingportion 134′. The screw receiving portion 134′ is shorter in length thanin the previous embodiment. A threaded blind bore 139 extends into thescrew receiving portion 134′ and is configured to receive the threadedportion 122 of the drive screw 120.

The ramp body 132′ of the driving ramp 130′ defines a pair of ramps 136′aligned with and configured to slidably engage the ramps 55 on thesecond endplate 40′. The ramp body 132′ also defines a pair of ramps137′ which are aligned with and configured to engage the ramps 35 on thefirst end plate 20′. Projections 138′ adjacent the ramps 136′, 137′extend into the grooves 37, 57 on the endplates 20′, 40′. Engagementbetween the projections 138′ and grooves 37, 57 maintains the drivingramp 130′ assembled to the endplates 20′, 40′ and guides movement of theendplates 20′, 40′ as the driving ramp 130′ is advanced.

Having generally described the components of the fixation device 10′,operation thereof will generally be described with reference to FIGS.12-16. The fixation device 10′ may be inserted at its fully collapsedheight as illustrated in FIGS. 12 and 13 to allow for easy insertioninto a collapsed interspinous space. As illustrated, in the collapsedposition, the extensions 123 and 125 are positioned in the respectivenotches 29, 49. During insertion, the spikes 66, 76 of the fixed plates60, 70 may be compressed into the respective spinous processes. Afterinsertion, the angular relation between the endplates 20′, 40′ isadjusted by rotating the drive screw 120 in an advancement direction.During initial advancement of the drive screw 120, engagement of theextensions 123, 125 in the notches 29, 49 prevents the central ramp 110′from advancing. Only the driving ramp 130′ is able to advance. As thedriving ramp 130′ advances, the ramps 35 ride up the ramps 136′ and theramps 55 ride up the ramps 137′. As illustrated in FIG. 14, such causesthe endplates 20′, 40′ to pivot relative to one another with the ends23′ and 43′ moving away from one another. Once the endplates 20′, 40′have pivoted a maximum amount (FIG. 14), the extensions 123, 125 areclear of the notches 29, 49. As such, with continued rotationaladvancement of drive screw 120, the central ramp 110′ is free to movetoward the driving ramp 130′, with the central ramp 110′ and the drivingramp 130′ drawn to one another, with the ramps 31′ riding up the ramps116′, the ramps 51′ riding up the ramps 117′, the ramps 35 riding up theramps 136′, the ramps 55 riding up the ramps 137′, and the forward ramps127, 129 riding along the inward ramps 36, 56, as illustrated in FIGS.15 and 16. Such movement causes the endplates 20′, 40′ to move away fromone another, thereby increasing the height of the fixation device 10 toget the desired fit, or used to distract the interspinous space torelieve pressure on neurological elements. As the endplates 20′, 40′pivot and then move away from one another, the fixed plates 60, 70 andsliding plates 80, 90 move in conformity therewith. After expansion ofthe endplates 20′, 40′, the sliding plates 80, 90 are moved along thelateral adjustment bars 28, 48 and compressed onto the spinousprocesses. Once positioned, the sliding plates 80, 90 are locked intoposition using the set screws 100.

The expandable fixation devices 10, 10′ may be manufactured from anumber of suitable biocompatible materials including, but not limitedto, titanium, stainless steel, titanium alloys, non-titanium metallicalloys, polymeric materials, plastics, plastic composites, PEEK,ceramic, elastic materials, or other suitable biocompatible materials.

In an exemplary embodiment, bone graft or similar bone growth inducingmaterial can be introduced around and/or within the fixation device 10,10′ to further promote and facilitate the intervertebral fusion. Thefixation device 10, 10′, in one embodiment, is preferably packed withbone graft or similar bone growth inducing material to promote thegrowth of bone through and around the fixation device. Such bone graftmay be packed between the endplates of the adjacent vertebral bodiesprior to, subsequent to, or during implantation of the fixation device.

Some advantages of the devices described in this disclosure are theability to insert a spinous process fusion implant at a reduced heightand then increase the height after insertion to achieve an accurateanatomical fit. Since the size of the implant is adjustable, it alsogreatly reduces the complexity of inserting an interspinous device sinceone device covers a wide range of implant sizes, negating the need forseveral variations of implant lengths and widths. The implant may bepreassembled, greatly reducing the number of steps required to insertthe device, which simplifies the overall procedure and reduces operatingroom time.

While the present disclosure has been described in terms of exemplaryaspects, those skilled in the art will recognize that the presentdisclosure can be practiced with modifications in the spirit and scopeof the appended claims. These examples given above are merelyillustrative and are not meant to be an exhaustive list of all possibledesigns, aspects, applications or modifications of the presentdisclosure.

What is claimed is:
 1. An apparatus comprising: a first endplate for anintervertebral implant, wherein the first endplate comprises a firstplate portion having a first upper surface and a first lower surface,wherein the first endplate further comprises first front ramped portionsextending away from the first lower surface and first rear rampedportions extending away from first lower surface, the first endplatehaving a first lateral adjustment arm extending from a first edgethereof; a second endplate for the intervertebral implant, wherein thesecond endplate comprises a second plate portion having a second uppersurface and a second lower surface, wherein the second endplate furthercomprises second front ramped portions extending away from the secondlower surface and second rear ramped portions extending away from secondlower surface, the second endplate having a second lateral adjustmentarm extending from a first edge thereof; a first fixed plate extendingalong a second edge of the first endplate opposite the first edgethereof, the first fixed plate extending substantially perpendicular tothe first endplate and having an inner surface defining a first spinousprocess engaging surface; a second fixed plate extending along a secondedge of the second endplate opposite the first edge thereof, the secondfixed plate extending substantially perpendicular to the second endplateand having an inner surface defining a second spinous process engagingsurface; a first sliding plate adjustably mounted on the first lateraladjustment arm such that the first sliding plate extends substantiallyperpendicular to the first endplate and has an inner surface defining athird spinous process engaging surface; a second sliding plateadjustably mounted on the second lateral adjustment arm such that thesecond sliding plate extends substantially perpendicular to the secondendplate and has an inner surface defining a fourth spinous processengaging surface; a central ramp positioned between the first endplateand the second endplate, wherein a body of the central ramp comprisesrear endplate engaging ramps; and a driving ramp positioned between thefirst endplate and the second endplate, wherein the driving rampcomprises front endplate engaging ramps; wherein the apparatus isconfigured such that movement of the central ramp and the driving ramptoward one another causes the first and second endplates to move apart,wherein each endplate has at least one notch adjacent each lateral edgeand the central ramp has extensions configured to engage the at leastone notch of each endplate, respectively, such that the central ramp isprevented from moving toward the driving ramp until the first and secondend plates have pivoted relative to one another.
 2. The apparatus ofclaim 1 wherein each spinous process engaging surface has a plurality ofspikes extending therefrom.
 3. The apparatus of claim 1 wherein eachsliding plate has a receiving bore configured to slidably receive arespective lateral adjustment arm.
 4. The apparatus of claim 3 whereineach receiving bore and corresponding lateral adjustment arm havecomplementary shapes such that the respective sliding plate is laterallyadjustable but rotationally fixed.
 5. The apparatus of claim 4 whereinthe complementary shape is a non-circular shape.
 6. The apparatus ofclaim 3 wherein each sliding plate includes a through bore incommunication with the receiving bore such that a set screw threadablyadjustable in the through bore is configured to engage the lateraladjustment arm received in the receiving bore.
 7. The apparatus of claim1 wherein a drive screw extends through the central ramp and intothreaded engagement with the driving ramp, and wherein, rotation of thedrive screw causes the driving ramp to move toward central ramp which isprevented from moving, thereby causing the first and second plates topivot relative to one another.
 8. The apparatus of claim 7 wherein afterpivoting of the first and second plates relative to one another,continued rotation of the drive screw causes the central ramp and thedriving ramp to move toward one another and the first and secondendplates to move apart at a fixed angular relationship.
 9. An apparatuscomprising: a first endplate for an intervertebral implant, the firstendplate having a first lateral adjustment arm extending from a firstedge thereof; a second endplate for the intervertebral implant, thesecond endplate having a second lateral adjustment arm extending from afirst edge thereof; a first fixed plate extending along a second edge ofthe first endplate opposite the first edge thereof, the first fixedplate extending substantially perpendicular to the first endplate andhaving an inner surface defining a first spinous process engagingsurface; a second fixed plate extending along a second edge of thesecond endplate opposite the first edge thereof, the second fixed plateextending substantially perpendicular to the second endplate and havingan inner surface defining a second spinous process engaging surface; afirst sliding plate adjustably mounted on the first lateral adjustmentarm such that the first sliding plate extends substantiallyperpendicular to the first endplate and has an inner surface defining athird spinous process engaging surface; a second sliding plateadjustably mounted on the second lateral adjustment arm such that thesecond sliding plate extends substantially perpendicular to the secondendplate and has an inner surface defining a fourth spinous processengaging surface; an expansion assembly positioned between the first andsecond endplates; the expansion assembly configured to selectively causethe first and second endplates to move apart wherein the expansionassembly includes a central ramp and a driving ramp interconnected toone another via a drive screw, the central ramp and the driving rampeach including ramped surfaces configured to engage ramped surfaces onthe first and second endplates wherein initial rotation of the drivescrew causes the driving ramp to move toward the central ramp such thatthe first and second endplates are caused to pivot relative to oneanother.
 10. The apparatus of claim 9 wherein each sliding plate has areceiving bore configured to slidably receive a respective lateraladjustment arm.
 11. The apparatus of claim 10 wherein each receivingbore and corresponding lateral adjustment arm have complementary shapessuch that the respective sliding plate is laterally adjustable butrotationally fixed.
 12. The apparatus of claim 11 wherein thecomplementary shape is a non-circular shape.
 13. The apparatus of claim10 wherein each sliding plate includes a through bore in communicationwith the receiving bore such that a set screw threadably adjustable inthe through bore is configured to engage the lateral adjustment armreceived in the receiving bore.
 14. The apparatus of claim 9 whereinrotation of the drive screw causes the central ramp and the driving rampto move toward one another, thereby engaging the ramped surfaces andcausing the first and second endplates to move away from one another.15. The apparatus of claim 9 wherein after pivoting of the first andsecond endplates relative to one another, continued rotation of thedrive screw causes the central ramp and the driving ramp to move towardone another and the first and second endplates to move apart at a fixedangular relationship.